The invention relates to a backlight module, and more particularly to a backlight module utilized in large-size liquid crystal display.
In a large-size liquid crystal display (such as a liquid crystal TV), the size of optical elements such as diffuser and prism plate is larger. Thus, deformation of the optical elements due to temperature variation is increased and worsens the optical characteristics thereof. Conventionally, various supporting structures are disposed in backlight modules to reduce the deformation of optical elements.
FIG. 1a shows a backlight module 10 disclosed in JP Patent No. 10-326517, which comprises supporting elements 14 disposed between a reflector 11 and a diffuser 12 to reduce the deformation of the diffuser 12. In JP Patent No. 10-326517, however, a gap is formed between the diffuser 12 and a housing (not shown) of the backlight module in a direction parallel to a planar surface of diffuser 12. Therefore, during deformation (expanding and shrinking) of the diffuser 12 due to temperature variation, the diffuser 12 rubs supporting elements 14 in a direction (as shown by the arrow in FIG. 1a) parallel to the planar surface of diffuser 12 producing particles and noise.
FIG. 1b shows a backlight module 100 disclosed in Taiwan Patent No. 591300, which comprises supporting elements 120 disposed on a reflector 110 to reduce the deformation of diffuser 140. The structure of supporting element 120 is complicated and increases the manufacturing cost of the backlight module. Additionally, lamps 130 are disposed on the supporting element 120 and thickness of the backlight module is thus increased.
FIG. 2a shows a backlight module disclosed in Taiwan Patent No. 592324, which reduces the deformation of the diffuser 23 with a supporting element 241 and a spring 24. The spring 24, however, only provides supporting force in a single direction (perpendicular to a planar surface of the diffuser 23), which is less effective.
FIG. 2b shows another backlight module disclosed in Taiwan Patent No. 592324, which further comprises a restrictive element 214 to improve the support thereof. However, as JP Patent No. 10-326517, the diffuser 232 in FIG. 2b rubs the supporting element 241 and produces particles and noise. Additionally, the spring 24 increases manufacturing cost and thickness of the backlight module.